If you don't do it now, you'll only regret it .
你如果现在不做，以后一定会后悔的。
The decision could be one he lives to regret .
这一决定也许会有让他后悔的一天。
‘I've had a wonderful life,’ she said, ‘I don't regret a thing.’
“我一辈子生活得很好，”她说，“我没什么可遗憾的。”
He bitterly regretted ever having mentioned it.
他非常懊悔提起那件事。
I deeply regret what I said.
我非常后悔说了那些话。
I regret that I never got to meet him in person.
很遗憾我始终没能见到他本人。
used to say in a polite or formal way that you are sorry or sad about a situation
The airline regrets any inconvenience.
航空公司对所造成的任何不便表示歉意。
I regret that I am unable to accept your kind invitation.
很遗憾，我不能接受你的友好邀请。
We regret to inform you that your application has not been successful.
我们很遗憾地通知您，您的申请未获通过。
It is to be regretted that so many young people leave school without qualifications.
遗憾的是那么多年轻人肄业离校。
It is with great regret that I accept your resignation.
接受你的辞呈，我感到非常遗憾。
She expressed her regret at the decision.
她对这个决定表示失望。
a pang/twinge of regret
一阵痛悔之情
I have no regrets about leaving Newcastle(= I do not feel sorry about it) .
我一点也不后悔离开纽卡斯尔。
What is your greatest regret(= the thing that you are most sorry about doing or not doing) ?
你最大的遗憾是什么？
He gave up teaching in 2009, much to the regret of his students.
他于 2009 年放弃了教学，这使他的学生深感遗憾。
1.遗憾,抱歉;后悔,悔恨;痛惜,惋惜,哀悼 (at; for; over; of)
2.〈美〉(对于邀请等的)婉言辞谢
1.悔恨,后悔,懊悔(过错,失去的机会等);以(不能...)为憾,抱歉,抱憾
2.怀念,想念(快乐的童年,故乡等);悼念,哀悼(死去的亲友等)
1.a feeling of sadness about something that has happened; a feeling of sadness about something that you wish you had not said or done
1.to feel sorry or sad that something has happened; to feel sorry or sad about something that you have said or done
1.Richard would be very, very happy with this event, and I deeply regret that he did not live to see it.
如果知道这件事（穆拉迪克被捕），理查德一定非常非常高兴，我很遗憾他没能活着看到这一幕。
2.Therefore, Beijing is often said to regret it too much, too early to Chongqing regret marriage.
所以，人们常说到北京后悔钱太少，到重庆后悔结婚太早。
3.You can expect all the "right" reasons & excuses to "take the easy way out" or to make lousy decisions you might later regret.
你可以靠正确的理由赶快逃脱，也可以做些糟糕的抉择等着将来后悔。
4.But I also guarantee that if I don't ask you to be mine, I'll regret for the rest of my life.
但是我同样坚信，假如今天不向你表白心迹，我会抱憾终生。
5.After that, I began to regret. I just waited to be changed into a cow.
事后我开始后悔，并等着变成一头牛。
6.There are going to be times where you pass on sex with a girl and you don't regret it for a second.
有时候你会拒绝一个女孩，而且事后你也不后悔。
7.Was that an important bit of intelligence that I will regret not knowing?
那是我不知道就会后悔的重要信息吗？
8.After the Divorce, I spent a few years obsessing about him and what Icould have done different, in regret.
离婚以后，我有好几年都沉浸在悔恨中，总是想着我是否可以做的不同，可以有不一样的结果。
9.He did not regret what he had said, but felt could have expressed it in a different way.
他并不后悔说过的话，只是觉得他完全可以不用这种方式表达。
10.Pahlavi said that if she has one regret it is that she did not spend more private time with her husband and children.
巴列维说如果她有遗憾的话，就是没有跟丈夫和孩子们一起相处更多时间。